Pin coupling based thermoelectric device

ABSTRACT

A thermoelectric device includes a flexible first substrate, and a number of sets of N and P thermoelectric legs coupled to the first substrate. Each set includes an N and a P thermoelectric leg electrically contacting each other through a conductive material on the first substrate. The thermoelectric device also includes a rigid second substrate, a conductive thin film formed on the second substrate, and a number of pins corresponding to the number of sets of N and P thermoelectric legs. Each pin couples the each set on an end thereof away from the first substrate to the conductive thin film formed on the second substrate, and is several times longer than a height of the N and P thermoelectric legs.

CLAIM OF PRIORITY

This Application is a Continuation and a Divisional Application of, andthereby claims priority to, co-pending patent application Ser. No.15/368,683 titled PIN COUPLING BASED THERMOELECTRIC DEVICE filed on Dec.5, 2016. The entirely of the disclosure thereof is incorporated herein.

FIELD OF TECHNOLOGY

This disclosure relates generally to thermoelectric devices and, moreparticularly, to a pin coupling based thermoelectric device.

BACKGROUND

A thermoelectric device may be formed from alternating N and Pelements/legs made of semiconducting material on a rigid substrate(e.g., alumina) joined on a top thereof to another rigid substrate/plate(e.g., again, alumina). However, a traditional implementation of thethermoelectric device may be limited in application thereof because ofrigidity, bulkiness, size and high costs (>$20/watt) associatedtherewith.

SUMMARY

Disclosed are a method, a device and/or a system of a pin coupling basedthermoelectric device.

In one aspect, a thermoelectric device includes a flexible firstsubstrate, and a number of sets of N and P thermoelectric legs coupledto the first substrate. Each set includes an N thermoelectric leg and aP thermoelectric leg electrically contacting each other through aconductive material on the first substrate. The thermoelectric devicealso includes a rigid second substrate, a conductive thin film formed onthe second substrate, and a number of pins corresponding to the numberof sets of N and P thermoelectric legs.

Each pin couples the each set on an end thereof away from the firstsubstrate to the conductive thin film formed on the second substrate,and is several times longer than a height of the N thermoelectric legand the P thermoelectric leg of the each set. A temperature differenceacross the N thermoelectric leg and the P thermoelectric leg of the eachset on the first substrate is controlled based on varying a height ofthe each pin, varying a thickness of the each pin and/or replacing theeach pin with another pin having a different area therefrom.

In another aspect, a thermoelectric device includes a flexible firstsubstrate, and a number of sets of N and P thermoelectric legs coupledto the first substrate. Each set includes an N thermoelectric leg and aP thermoelectric leg electrically contacting each other through aconductive material on the first substrate. The thermoelectric devicealso includes a rigid second substrate, a conductive thin film formed onthe second substrate, and a number of pins corresponding to the numberof sets of N and P thermoelectric legs.

Each pin couples the each set on an end thereof away from the firstsubstrate to the conductive thin film formed on the second substrate,and is several times longer than a height of the N thermoelectric legand the P thermoelectric leg of the each set. Heat or cold is configuredto be applied at an end of the first substrate or the second substrate.In accordance with the application of the heat or the cold at the end ofthe first substrate or the second substrate, a temperature differenceacross the N thermoelectric leg and the P thermoelectric leg of the eachset on the first substrate is controlled based on varying a height ofthe each pin, varying a thickness of the each pin and/or replacing theeach pin with another pin having a different area therefrom.

In yet another aspect, a thermoelectric device includes a flexible firstsubstrate, and a number of sets of N and P thermoelectric legs coupledto the first substrate. Each set includes an N thermoelectric leg and aP thermoelectric leg electrically contacting each other through aconductive material on the first substrate. The thermoelectric devicealso includes a rigid second substrate, a conductive thin film formed onthe second substrate, and a number of pins corresponding to the numberof sets of N and P thermoelectric legs.

Each pin couples the each set on an end thereof away from the firstsubstrate to the conductive thin film formed on the second substrate,and is several times longer than a height of the N thermoelectric legand the P thermoelectric leg of the each set. Further, thethermoelectric device includes a set of terminals formed on the firstsubstrate to measure potential difference generated based on applicationof heat or cold at an end of the thermoelectric device. A temperaturedifference across the N thermoelectric leg and the P thermoelectric legof the each set on the first substrate is controlled based on varying aheight of the each pin, varying a thickness of the each pin and/orreplacing the each pin with another pin having a different areatherefrom.

The methods and systems disclosed herein may be implemented in any meansfor achieving various desired aspects of thermoelectric devicesdisclosed herein for applications including but not limited to wearabledevices, automotive devices and/or components, solar devices andInternet of Things (IoT).

Other features will be apparent from the accompanying drawings and fromthe detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of this invention are illustrated by way of example andnot limitation in the figures of the accompanying drawings, in whichlike references indicate similar elements and in which:

FIG. 1 is a schematic view of a thermoelectric device.

FIG. 2 is a schematic view of an example thermoelectric device withalternating P and N elements.

FIG. 3 is a top schematic view of a thermoelectric device component,according to one or more embodiments.

FIG. 4 is a front schematic view of a thermoelectric device includingthe thermoelectric device component of FIG. 3, according to one or moreembodiments.

FIG. 5 is a schematic view of a solar panel device configured to havethe thermoelectric device of FIG. 4 integrated therein.

FIG. 6 is a circuit diagram representation of a hybrid device includingthe solar panel device of FIG. 5 and the thermoelectric device of FIG. 4integrated therein.

FIG. 7 is a schematic view of a flat plate collector, according to oneor more embodiments.

FIG. 8 is a process flow diagram detailing the operations involved inrealizing the thermoelectric device of FIG. 4, according to one or moreembodiments.

FIG. 9 is another front schematic view of the thermoelectric device ofFIG. 4 including the thermoelectric device component of FIG. 3 withpins, according to one or more embodiments.

Other features of the present embodiments will be apparent from theaccompanying drawings and from the detailed description that follows.

DETAILED DESCRIPTION

Example embodiments, as described below, may be used to provide amethod, a device and/or a system of a pin coupling based thermoelectricdevice. Although the present embodiments have been described withreference to specific example embodiments, it will be evident thatvarious modifications and changes may be made to these embodimentswithout departing from the broader spirit and scope of the variousembodiments.

FIG. 1 shows a thermoelectric device 100. Thermoelectric device 100 mayinclude different metals, metal 1 102 and metal 2 104, forming a closedcircuit. Here, a temperature difference between junctions of saiddissimilar metals leads to energy levels of electrons therein shifted ina dissimilar manner. This results in a potential/voltage differencebetween the warmer (e.g., warmer junction 106) of the junctions and thecolder (e.g., colder junction 108) of the junctions. The aforementionedconversion of heat into electricity at junctions of dissimilar metals isknown as Seebeck effect.

The most common thermoelectric devices in the market may utilizealternative P and N type legs/pellets/elements made of semiconductingmaterials. As heat is applied to one end of a thermoelectric devicebased on P and N type elements, charge carriers thereof may be releasedinto the conduction band. Electron (charge carrier) flow in the N typeelement may contribute to a current flowing from the end (hot end) wherethe heat is applied to the other end (cold end). Hole (charge carrier)flow in the P type element may contribute to a current flowing from theother end (cold end) to the end (hot end) where the heat is applied.Here, heat may be removed from the cold end to prevent equalization ofcharge carrier distribution in the semiconductor materials due tomigration thereof.

In order to generate voltage at a meaningful level to facilitate one ormore application(s), typical thermoelectric devices may utilizealternating P and N type elements (legs/pellets) electrically coupled inseries (and thermally coupled in parallel) with one another, as shown inFIG. 2. FIG. 2 shows an example thermoelectric device 200 includingthree alternating P and N type elements 202 ₁₋₃. The hot end (e.g., hotend 204) where heat is applied and the cold end (e.g., cold end 206) arealso shown in FIG. 2.

Typical thermoelectric devices (e.g., thermoelectric device 200) may belimited in application thereof because of rigidity, bulkiness and highcosts (>$20/watt) associated therewith. Also, these devices may operateat high temperatures using active cooling. Exemplary embodimentsdiscussed herein provide for a thermoelectric platform (e.g., enabledvia roll-to-roll sputtering on a substrate (e.g., plastic)) that offersa large scale, commercially viable, high performance, easy integrationand inexpensive (<20 cents/watt) route to flexible thermoelectrics.

In accordance with the exemplary embodiments, P and N thermoelectriclegs may be deposited on a flexible substrate (e.g., plastic) using aroll-to-roll process that offers scalability and cost savings associatedwith the N and P materials. In a typical solution, bulk legs may have aheight in millimeters (mm) and an area in mm². In contrast, N and P bulklegs described in the exemplary embodiments discussed herein may have aheight in microns (μm) and an area in the μm² to mm² range.

FIG. 3 shows a top view of a thermoelectric device component 300,according to one or more embodiments. Here, in one or more embodiments,a number of sets of N and P legs (e.g., sets 302 _(1-M) including N legs304 _(1-M) and P legs 306 _(1-M) therein) may be deposited on asubstrate 350 (e.g., plastic) using a roll-to-roll process discussedabove. FIG. 3 also shows a conductive material 308 _(1-M) contactingboth a set 302 _(1-M) and substrate 350, according to one or moreembodiments; an N leg 304 _(1-M) and a P leg 306 _(1-M) of a set 302_(1-M) electrically contact each other through conductive material 308_(1-M).

FIG. 4 shows a front view of thermoelectric device 400 includingthermoelectric device component 300, according to one or moreembodiments. Here, in one or more embodiments, a pin 402 _(1-M) severaltimes longer than the height of each of the N legs 304 _(1-M) and P legs306 _(1-M) may couple an N leg 304 _(1-M) and a P leg 306 _(1-M) withina set 302 _(1-M) on an end of the set 302 _(1-M) away from substrate 350to a conductive thin film 404. In one or more embodiments, conductivethin film 404 may be formed on another substrate 450 (e.g., plastic,same substrate as substrate 350, a substrate (e.g., flexible, rigid)different from substrate 350).

In other words, in one or more embodiments, the sets 302 _(1-M) may besandwiched between substrate 350 and substrate 450 by way of conductivematerial 308 _(1-M), pins 402 _(1-M) and conductive thin film 404. Inone example embodiment, conductive thin film 404 may be formed onsubstrate 450 through sputtering. Other ways of forming conductive thinfilm 404 on substrate 450 are within the scope of the exemplaryembodiments discussed herein. Also, it should be noted that the sets 302_(1-M) may, alternately, be attached/coupled to a rigid substrate suchas substrate 350 instead of being sputtered onto a flexible substratesuch as substrate 350. In other words, substrate 350 may be a rigidsubstrate or a flexible substrate.

In one or more embodiments, pins 402 _(1-M) may be pogo pins commonlyused in probe cards in the semiconductor industry for testing wafers.Pogo pins are well known to one skilled in the art; therefore, detaileddiscussed associated therewith has been skipped for the sake ofconvenience. In one or more embodiments, FIG. 3 shows terminals (370,372) to measure the potential difference generated based on heat (or,cold) applied at an end of thermoelectric device 400. It is obvious thatheat (or, cold) may be applied at any end of thermoelectric device 400;in other words, the heat (or, the cold) may be applied at an end ofsubstrate 350 or substrate 450.

In one or more embodiments, a thermoelectric module (e.g.,thermoelectric device 400) with the pin setup may offer severaladvantages over a traditional implementation. In one or moreembodiments, a temperature difference across the thermoelectric P and Nlegs may be controlled by varying a height, a thickness and/or an areaof pins 402 _(1-M) (each of pins 402 _(1-M) whose height, thicknessand/or area can be varied may be used). The modularized approach tothermoelectric device 400 may provide for replacing pins 402 _(1-M) withanother set thereof having a different height of constituent individualpins, a different thickness of constituent individual pins and/or adifferent area of constituent individual pins. In one exampleimplementation, the height of each pin 402 _(1-M) may be adjustedthrough a spring associated therewith.

In one or more embodiments, the controllability of the height, thethickness and/or the area of pins 402 _(1-M) may allow thermoelectricdevice 400/module to operate at higher temperatures and a widertemperature spectrum compared to a traditional implementation thereof.In the traditional implementation, the height of the P and N legs may befixed based on material costs and performance. Exemplary embodimentsdiscussed herein may offer scalability and cost savings.

Exemplary embodiments discussed herein (e.g., thermoelectric device 400)may also offer easy integration with respect to solar and solar thermalapplications. As discussed above, the traditional thermoelectric modulemay have a size limitation and may not scale to a larger area. Forexample, a typical solar panel may have an area in the square meter (m²)range and the traditional thermoelectric module may have an area in thesquare inch range. A thermoelectric module in accordance with theexemplary embodiments may be of varying sizes and/or dimensions rangingfrom a few mm² to a few m².

For efficient harnessing of solar energy, optimum hybridization ofphotovoltaic (PV) and thermoelectric devices may be considered ideal. Inthe PV operation, ˜40% of solar spectral irradiance may spontaneously betransformed into heat by thermalization loss of high energy photons andtransmission loss of low energy photons. Therefore, additional energyharvesting from waste heat may be useful not only for increasingefficiency but also for removing unwanted heat that prevents efficientPV operation. Achieving lossless coupling may enable the power outputfrom the hybrid device be equal to the sum of the maximum power outputsproduced separately from individual PV and thermoelectric devices.

FIG. 5 shows a solar panel device 500. Solar panel device 500 mayinclude a glass sheet 502 (e.g., tempered low iron glass) under which alayer of interconnected solar cells 504 may be sandwiched betweenlamination layers (506, 508). In one implementation, the laminationlayers (506, 508) may be made of ethyl vinyl acetate (EVA) films. Theframework for solar panel device 500 may be provided by a backsheet 510,which lies underneath lamination layer 508. It should be noted thatother implementations of solar panel device 500 are within the scope ofthe exemplary embodiments discussed herein.

In one or more embodiments, a thermoelectric module 550 (e.g.,thermoelectric device 400) may be coupled to the layer of interconnectedsolar cells 504 between said layer of interconnected solar cells 504 andlamination layer 508 to realize the hybrid device discussed above. FIG.6 shows a circuit diagram representation of a hybrid device 600 (e.g.,solar panel device 500 with thermoelectric module 550 of FIG. 5),according to one or more embodiments. In one or more embodiments, solarpanel device 500 may be represented as a current source 602 in parallelwith a diode 604 and a shunt resistance R_(SH) 606. In one or moreembodiments, the series resistance representation of solar panel device500 is shown as R_(S) 608 in FIG. 6. In one or more embodiments,thermoelectric module 550 may be represented by a voltage source 612 inseries with an internal resistance R_(I) 614. FIG. 6 also shows that theoutput voltage of hybrid device 600 to be the sum of the voltage ofsolar panel device 500 (V_(SOLAR)) and the voltage of thermoelectricmodule 550 (V_(TM)).

Solar thermal collectors may be of several types including but notlimited to flat plate collectors, evacuated tube collectors, IntegralCollector Storage (ICS) system based collectors, thermosiphon basedcollectors and concentrating collectors. The most common type of solarthermal collectors may be flat plate collectors. FIG. 7 shows a flatplate collector 700, according to one or more embodiments. In one ormore embodiments, flat plate collector 700 may include a glass plate 702(e.g., tempered glass) on top and an absorber plate 704 (e.g., copperbased, aluminum based) on a bottom thereof. Sunlight may pass throughglass plate 702 and heat up absorber plate 704; solar energy may therebybe converted into heat energy. The heat may be passed onto liquidpassing through pipes 706 attached to absorber plate 704.

The working of a typical flat plate collector is well known to oneskilled in the art. Detailed discussion associated therewith has,therefore, been skipped for the sake of convenience. FIG. 7 showsinsulation 708, header 710, inlet 712 and outlet 714 of flat platecollector 700 merely for the sake of completeness. It should be notedthat glass plate 702 may, instead, be replaced with a polymer coverplate. Other implementations of flat plate collector 700 are within thescope of the exemplary embodiments discussed herein.

In one or more embodiments, a thermoelectric module 750 (e.g.,thermoelectric device 400; analogous to thermoelectric module 550) maybe integrated into flat plate collector 700 (an example solar thermalcollector) at the back of absorber plate 704 (or underneath absorberplate 704). In one or more embodiments, in the case of a pure waterheater system implementation, flat plate collector 700 includingthermoelectric module 750 may produce electricity in addition to thermalenergy to be used for lighting and other purposes; said thermal energymay also heat water at the same time. As absorber plate 704 reachestemperatures in the vicinity of 400 degrees Celsius (C), there may be alot of temperature gradients to be exploited and harvested throughthermoelectric module 750.

FIG. 8 shows a process flow diagram detailing the operations involved inrealizing a pin coupling based thermoelectric device (e.g.,thermoelectric device 400), according to one or more embodiments. In oneor more embodiments, operation 802 may involve coupling a number of sets(e.g., sets 302 _(1-M)) of N (e.g., N legs 304 _(1-M)) and P (e.g., Plegs 306 _(1-M)) thermoelectric legs on a substrate (e.g., substrate350). In one or more embodiments, the each set may include an Nthermoelectric leg and a P thermoelectric leg electrically contactingeach other through a conductive material (e.g., conductive material 308_(1-M)) on the substrate.

In one or more embodiments, operation 804 may involve forming aconductive thin film (e.g., conductive thin film 404) on anothersubstrate (e.g., substrate 450). In one or more embodiments, operation806 may then involve coupling the each set on an end thereof away fromthe substrate to the conductive thin film formed on the anothersubstrate through a pin (e.g., pin 402 _(1-M)) several times longer thana height of the N thermoelectric leg and the P thermoelectric leg of theeach set to form/realize the thermoelectric device (e.g., thermoelectricdevice 400).

FIG. 9 shows another front schematic view of thermoelectric device 400including thermoelectric component 300 with pins 402 _(1-M), accordingto one or more embodiments. Here, the connection of pins 402 _(1-M) to Nlegs 304 _(1-M) and P legs 306 _(1-M) within sets 302 _(1-M) onsubstrate 350 is shown. Also, FIG. 9 shows connection of said pins 402_(1-M) to conductive thin film 404 on substrate 450. The perspectiveview (second of two views in FIG. 9) of thermoelectric device 400 inFIG. 9 omits the physical depiction of terminals (370, 372) merelybecause the surface of substrate 350 across which N legs 304 _(1-M) andP legs 306 _(1-M) are deposited is crowded. However, terminals (370,372) are depicted as lines with polarities. The location of terminals(370, 372) on the surface of substrate 350 in the perspective view ofthermoelectric device 400 can easily be deduced from location thereof onthermoelectric component 300 (first view in FIG. 9) in both FIG. 9 andFIG. 3.

It should be noted that the exemplary embodiments discussed above do notlimit application thereof to solar devices (e.g., hybrid solar device600, flat plate collector 700). For example, in low temperatureapplications such as harvesting body heat in a wearable device, amilli-volt (mV) output of thermoelectric device 400 may be boosted usinga Direct Current (DC)-DC converter to a desired voltage output (e.g.,3.3 V) to augment a life of a battery used or to replace said battery.Also, it should be noted that additional electronics and/or wiring maybe needed to integrate thermoelectric device 400 within a device/systemassociated with relevant applications (e.g., automotivedevices/components, Internet of Things (IoT).

Although the present embodiments have been described with reference tospecific example embodiments, it will be evident that variousmodifications and changes may be made to these embodiments withoutdeparting from the broader spirit and scope of the various embodiments.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

What is claimed is:
 1. A thermoelectric device comprising: a flexiblefirst substrate; a plurality of sets of N and P thermoelectric legscoupled to the first substrate, each set comprising an N thermoelectricleg and a P thermoelectric leg electrically contacting each otherthrough a conductive material on the first substrate; a rigid secondsubstrate; a conductive thin film formed on the second substrate; and aplurality of pins corresponding to the plurality of sets of N and Pthermoelectric legs, each pin coupling the each set on an end thereofaway from the first substrate to the conductive thin film formed on thesecond substrate, and the each pin being several times longer than aheight of the N thermoelectric leg and the P thermoelectric leg of theeach set, wherein a temperature difference across the N thermoelectricleg and the P thermoelectric leg of the each set on the first substrateis controlled based on at least one of: varying a height of the eachpin, varying a thickness of the each pin and replacing the each pin withanother pin having a different area therefrom.
 2. The thermoelectricdevice of claim 1, wherein the plurality of sets of N and Pthermoelectric legs is deposited on the first substrate through aroll-to-roll sputtering process.
 3. The thermoelectric device of claim1, wherein the conductive thin film is formed on the second substratethrough sputtering.
 4. The thermoelectric device of claim 1, wherein theeach pin is a pogo pin.
 5. The thermoelectric device of claim 1, whereinone of: heat and cold is configured to be applied at an end of the firstsubstrate.
 6. The thermoelectric device of claim 5, further comprising aset of terminals formed on the first substrate to measure potentialdifference generated based on the application of the one of: the heatand the cold to the end of the first substrate.
 7. The thermoelectricdevice of claim 1, wherein one of: heat and cold is configured to beapplied at an end of the second substrate.
 8. The thermoelectric deviceof claim 7, further comprising a set of terminals formed on the firstsubstrate to measure potential difference generated based on theapplication of the one of: the heat and the cold to the end of thesecond substrate.
 9. A thermoelectric device comprising: a flexiblefirst substrate; a plurality of sets of N and P thermoelectric legscoupled to the first substrate, each set comprising an N thermoelectricleg and a P thermoelectric leg electrically contacting each otherthrough a conductive material on the first substrate; a rigid secondsubstrate; a conductive thin film formed on the second substrate; and aplurality of pins corresponding to the plurality of sets of N and Pthermoelectric legs, each pin coupling the each set on an end thereofaway from the first substrate to the conductive thin film formed on thesecond substrate, and the each pin being several times longer than aheight of the N thermoelectric leg and the P thermoelectric leg of theeach set, wherein one of: heat and cold is configured to be applied atan end of one of: the first substrate and the second substrate, andwherein, in accordance with the application of the one of: the heat andthe cold at the end of the one of: the first substrate and the secondsubstrate, a temperature difference across the N thermoelectric leg andthe P thermoelectric leg of the each set on the first substrate iscontrolled based on at least one of: varying a height of the each pin,varying a thickness of the each pin and replacing the each pin withanother pin having a different area therefrom.
 10. The thermoelectricdevice of claim 9, wherein the plurality of sets of N and Pthermoelectric legs is deposited on the first substrate through aroll-to-roll sputtering process.
 11. The thermoelectric device of claim9, wherein the conductive thin film is formed on the second substratethrough sputtering.
 12. The thermoelectric device of claim 9, whereinthe each pin is a pogo pin.
 13. The thermoelectric device of claim 9,further comprising a set of terminals formed on the first substrate tomeasure potential difference generated based on the application of theone of: the heat and the cold to the end of the one of: the firstsubstrate and the second substrate.
 14. A thermoelectric devicecomprising: a flexible first substrate; a plurality of sets of N and Pthermoelectric legs coupled to the first substrate, each set comprisingan N thermoelectric leg and a P thermoelectric leg electricallycontacting each other through a conductive material on the firstsubstrate; a rigid second substrate; a conductive thin film formed onthe second substrate; a plurality of pins corresponding to the pluralityof sets of N and P thermoelectric legs, each pin coupling the each seton an end thereof away from the first substrate to the conductive thinfilm formed on the second substrate, and the each pin being severaltimes longer than a height of the N thermoelectric leg and the Pthermoelectric leg of the each set; and a set of terminals formed on thefirst substrate to measure potential difference generated based onapplication of one of: heat and cold at an end of the thermoelectricdevice, wherein a temperature difference across the N thermoelectric legand the P thermoelectric leg of the each set on the first substrate iscontrolled based on at least one of: varying a height of the each pin,varying a thickness of the each pin and replacing the each pin withanother pin having a different area therefrom.
 15. The thermoelectricdevice of claim 14, wherein the plurality of sets of N and Pthermoelectric legs is deposited on the first substrate through aroll-to-roll sputtering process.
 16. The thermoelectric device of claim14, wherein the conductive thin film is formed on the second substratethrough sputtering.
 17. The thermoelectric device of claim 14, whereinthe each pin is a pogo pin.
 18. The thermoelectric device of claim 14,wherein the one of: the heat and the cold is configured to be applied atan end of the first substrate.
 19. The thermoelectric device of claim14, wherein the one of: the heat and the cold is configured to beapplied at an end of the second substrate.
 20. The thermoelectric deviceof claim 14, wherein the height of the each pin is adjusted through aspring associated therewith.